Spark-gap apparatus



L. J. LESH SPARK GAP APPARATUS Filed June 5, 1918 1mm/ron J4- 4/1/4 m4 i L; Aronmfr Patented Apr. 10, 1923.

LAWRENCE J.. LESH, OIF-NEW YORK, N. Y., ASSIGNOR TO YORK, N'. Y.

EMIL J. s'IMoN, or NEW SPARK-GAP APPARATUS.

Application led June 5,

To all whom t may concern:

Be it known that I, LAWRENCE J. LEsH, a citizen ofthe United States, residing at New York cit in the county-of New York and State of ew York, have invented certain new and 'useful Improvements in Spark-Gap Apparatus, fully described and represented in the following specification and the accompanying drawings, forming a part of the same.

V This invention relates to spark gap apparatus for use in radio transmitting and receiving sets. More particularly, the inventionrelates to spark gap apparatus of the multiple unit gap type, and the invention aims generally to provide improved apparatus of this 4type ofv simple and compact construction in whichthe spark gap units ma'y be readily removed and replaced and which shall provide for convenient adjustment of the circuit for connecting any desired number of the units in the circuit, and to provide an improved spark gap unit. T'he invention consists in the features of construction, arrangement and combinations of parts herein disclosed and specifically pointed out inl the claims.

' A full -understanding of the invention can best be given by a detailed descriptionof an approved construction embodying the various features of the invention and a modification thereof, and such a description will now be given in connection with the accompanying drawings, in which:-

Fig. 1 is a View partly in side elevation and partlyin section-on line 1--1 of Fig. 2 of a multiple spark gap apparatus made in accordance with the invention; i

Fig. 2 is a rear view of the main of the apparatus shown in Fig. 1;

Fig. 3 is ,an enlarged broken sectional View of oneof thespark gap units and its holder and adjacent parts of the apparatus taken on line 3 3 of Fig. l;

Fig. 4 is a detail view looking in the same direction as in Fig. 2 and showing a portion of the cylindrical support with the near standard broken away;

Fig. 5 is a View in elevation and on a smaller scale than Fig. 3 of a spark gap unit and its holder of slightly modiiied construction; and

Fig. 6 is avertical section of the'construction shown in Fig. 5.

portion Referring to the drawings, and first to 1818. ASerial- N0. 238,310.

Figs. 1` to 3, the apparatus shown comprises a plurality of unit spark gaps 10 and holding and clrcuit controlling apparatus therefor. The unit spark gaps shown are each of the single sparking space type, although features of the invention embodied therein are obviously not limited to a single sparking space, or two-plate, gap, and .comprise each two electrode plates and 16 of heatconducting and electricity-conducting material which may be of circular or other suitable form, each plate being formed at its inner face with a flat annular seat to which is secured an annular electrode or sparking plate 17 and with an annular bearing face 18 surrounding the sparking plate and separated therefrom by an annular channel 19. The plates are secured together with an annular gasket 20 of fish paper impregnated with linseed oil and beeswax, or other suitable insulating and air-excluding material, between their bearing faces by means of a single central screw bolt which extends through an opening in the plate 15 and through the openings in the sparking plates and screws into a threaded opening in the electrode plate 16. The central openings of the sparking plates are of such size that the inner edges of the plates are spaced off some distance from the screw bolt, and the central portion of'the inner face of the electrode plate 16 is desirably formed with a depression 26, as shown.y The central bolt opening in the plate 15 is of such size that the bolt is suitably spaced away from the sides of the opening, and a bushing 27 provides a bearing for the head of the bolt, this bushing being formed of insulating material suitable to form an air-excluding packing between the bolt head and the electrode plate, such; for example, as suitable hard fiber, bakelite delecto, etc. In order to prevent the entrance of air past the threaded end of the bolt, the threaded opening in the electrode plate 16 which receives the end of the bolt is desirably a blind opening extending from the inner face of the plate but not all the way through the same` as shown. The sparking plates. or electrodes, 17 may be riveted or otherwise secured to the electrode seats of the gap plates and in the assembled gap have their sparking faces parallel and spaced slightly apart to provide the necessary sparking space between them.

The use of asingle centrally located clamping bolt, or other clamping -means bearing centrally on the electrode plates for securing the plates together, has the advantage of simplicity and cheapness of construction, while at the same time providing a spark ga unit the parts of which may be very casi y and readily assembled or separated, and insuring even pressure between the bearing faces of the plates. It may be noted that the arrangement shown having annular sparking surfaces and a single center. bolt necessitates a packing for excluding air from the space within the inner edges of the sparking surfaces as well as the usual packing for excluding air from the space around the outer edges of the sparking surfaces, such inner packing in the construction shown being the bushin 27.

The lprovision of spar ing plates of annu# lar form or of other suitable form having their central portion removed and having most desirably continuously curved inner and outer edges, in addition to the advantage of permitting the use of a central bolt or other centrally located clamping means for securin the gap plates together, has also other advantages and may obviously be used in connection with spark gap units having clamping means which do not extend centrally between the plates. I have found that the use of such annular electrodes results -in the voltage remaining constant under a longer continued operation than when the center of the electrodes is not removed.

' This improved result is probably due to the fact that the use of sparking plates of this form avoids or at least reduces the warping or buckling of the plates resulting from the action of heat on metals of dissimilar coefficients of expansion and also possibly to the better` discharge of heat from the plates. The sparking plates or electrodes should be made from a metal of high thermal and electrical conductivity, plates of silver being usually used. The gap plates on which the electrodes are mounted are usually made of brass or other metal of suitable strength and not too expensive. ,j

The spark gap units are supported in radial arrangement flatwise to each other in a series of radially arranged holders carried by a support 30 the supporting surface of which extends in a curve of constant radius and which is most desirably extended to form a complete circle and is best formed by a cylindrical plate of suitable insulating mal terial such as bakelite delecto. The cylindrical supporting plate 30 is carried by a pair of standards 31 which extend one on each end of the supporting cylinder 30 diametrically across the same and radially therefrom, downward in the construction shown, to the base-plate or other structure on which the apparatus is mounted. The holders,

which extend radially `from the cylindrical' support 30, each comprises a pair of springconducting arms 35 and 36 for bearing on opposite sides of a spark gap unit. The spark gap units in the form shown in Figs.

1 to 3 are formed on each side with a central arms of adjoining holders being electrically connected, as by forming such adjacent arms of adjoining holders of a single piece of metal bent into U form, the connecting portion of the metal between the two arms providing means for conveniently securing the arms to the support 30 by bolts 38, as shown. The arms of each holder are insulated from each other when a gap unit is in position between them except for the sparking action across the gap. lVhen all the holders are provided with spark gap units fitted therein, the gap units will, therefore, be electrically connected in series. In order that the series connection between the gap units shall not be broken by the removal of any one or more gap units, the holder arms are set under such spring tension that the arms'of each holder will, when nothing is interposed between them, move together and bear against each other to close the circuit at such holder. Because of the relative thickness of the gap .units illustrated, the holder arms are desirably extended a substantial distance outward beyond their openings 37 and curved somewhat toward each other to insure, when the gap unit is removed, a good contact pressure between the arms without necessitating the arms being under too great tension when the gap unit 'is in position. The extreme outer ends of the arms of each holder are bent slightly outward or away from each other to permit the gap unit to be more readily entered between them. Obviously, the series connection between adjoining holders must not extend to the outer arms of the end holders of the series, that is, the two lowermost holders in the construction shown which support gap units on either side of the standards 31. The outer arrnsof these two end holders are, therefore, formed of separate pieces of metal, the inner ends of which may be secured to the cylindrical support 30 in any suitable manner, as by means of" llO flanges at their inner ends bolted to the sup- 1 port by bolts 38a and 38b respectively.

Connection from one side of the circuit is made to the outer arm of one of the endholders of the series by a connection te the bolt 38B. The bolts as and the belt as 'are each formed at their inner ends to serve as a contact terminal, providing a series of terminals to which connection may be made for connecting in the circuit any desired number .of the holders and gap units carried thereby. Variable connection .to such contact `terminals 40 is made by means otV a swinging contact arm 41 which is carried by ashaft 42 journalled in the side plates 31 formed with a concave or cup-shaped bearing face to fit down over the convex louter faces of the terminals 40, which are of ball or rounded knob form. The contact piece thus gives an extended contact and also serves, being spring-pressed, to accurately position the, contact piece and arm with respect to any terminal 40 and yieldingly resist turning movement of the contact arm from any position of contact, and also to indicate manually to the operator when the arm has been moved into position to bring its contact piece into register with and proper contact relation with any desired terminal. In order that the slight resistance to turning ofthe shaft 42 which serves as a manual indication of correct position of the Contact arm shall occur only when the arm has been moved to bring its contact -piece into register and proper contact relation with on'of thefterminals 40, the contact piece 43l is so formed or extended laterally as shown with regard to the relative position or spacing of the terminals 40 that when the contact piece has been pushed back by the turning movement of 'its arm to carry it from engagement with one of the terminals into engagement with an adjacent terminal it will come into engagement with the adjacent terminal while still held against forward movement by engagement with the terminal from which it is being moved. The swinging contact arm 41 is of conducting material and is in conducting engagement with the shaft 42 which is also of conducting material, and circuit connection to the arm 41 is made through a contact spring 45- bearing on the shaft and to which one of the circuit wires is connected, as shown in Fig. 2. By turning the -shaft 42 to swing the contact arm 41, the number of gap holders connected in the circuit may be increased or decreased according to thedirection in which the shaft and arm are turned.

The arrangement of the gap holders to support the gap units in radial -arrangement and atwise to eachother, in addition to other advantages, provides for the free movement of air betweenl the gap units vwhich is desirable for cooling the units. In

in operation, the outer surface of the'gap plates is desirably formed with radial ribs which provide an increased heat dissipating surface. Such form of outer surface of the gap plates is especially suitable for gap units of the form shown which, on account ofthe clamping pressure on the gap plates being exerted at the center of the plates, must, in order to resist deformation .with resulting loss of parallelism between the sparking surfaces, be made of greater strength and, therefore, of greater thickness especially at the center than plates of gap units of the form commonly used heretofore having clampin screws distributed at or near the -outer e ges of the plates. Increased thickness ofthe gap plates is also desirable in order to accommodate a central screw bolt of suitable size. By cutting away portions of the material of the outer face of the plates between the central portion and the portion about the outer channels 19, and

y leaving suitably spaced ribs 55 between such cut-awa portions, an increase in the hea-t dissipating surface is secured, while at the same time the ribs serve also as strengthening ribs to resist deformation of the plates under pressure, j giving the necessary strength with less weight of metal than would otherwise be required.' v

Figs. 5 and 6 illustrate a spark gap unit having a slightly diiferent formation -of-the outer sides of its gap plates and an alternative form of holder.y Asv shown in these views, the spring arms 35.and 36, of the holder do not extend past the center of the gap unit but only into the depressions be.- tween adjacent radial ribs on the outside of the gap plates. The spring arms may be formed near their outer ends withv knobs or bosses to extend into recesses 61 formed in the gap plates. The ends of the arms are desirably shaped to fit the spaces or recesses between adjacent radial ribs o'f the gap plates,' and the gap plates are desirably formed with a recess 61'in each of the spaces between adjacentradial ribs so that the gap unit may be placed in a holder with theholder larms extending between any two ada flow of air against4 and between is not to be limited to the exact construction,

the apparatus shown may be employed independently of other parts thereof. What is claimed'is:

1.. Spark gap apparatus, comprising a plurality' o f gap unit holders electrically connected in series, each holder being formed of a pair of spring conducting arms which are under tension to bear against each other to close the circuit across the holder when there is no ap unit in place therein', a series of terminas on the inner side of the cylindrical support, two such terminals being electrically connected one to the outer spring contact piece of each end holder and the others of said terminals being connected each to the adjacent spring contact pieces of two adjoining holders, and means for connecting said terminals in the circuit including a contact member movable about the axis of said cylindrical support to vary to'bear against and support a gap unit and the number of gap holders connected in through which electrical connection is made \the circuit.

to the opposite sides of the gap unit, said sp-ring arms being formed of flat spring metal each having anopening to receive a.

boss on the side of the gap unit and an extension beyond the opening, said arms being under tension to move into engagement with each other to bring their extensions into engagement to close the circuit -across the holder when there isno gap unit in position in the holder.

2. Spark gap apparatus, comprising .a plurality of gap unit holders electrically connected in series, each holder being formed of a pair of spring conducting arms' to bear against and support a gap unit and through which electrical connection is made to the opposite sides of the gap unit and which are formed to close the circuit across the holder when there is no gap'unit in position in the holder, anda plurality of gap units inthe holders which have their electrode plates held together by a single center screw bolt for each gap unit, the gap units and the holder arms being` formed with coacting parts for preventing acciden-A Vtal displacement of a gap unit relatively to its holder by engagement on a radius extending from the center screw bolt of the gap unit.

3. Spark gap apparatus, comprising a support having a supporting surface extending in a curve of constant radius, a plurality of gap unit holders mounted on the supporting surface of the support arranged to support a series of gap units in radial arrangement and iatwise to eachother, aplurality ofterminals'through which connection may be made for connecting any desired number of the gap units in the circuit, and a contact member movable relatively to said terminals to vary the number of gap units connected in the circuit.

4. Spark gap apparatus, comprising a cylindrical support of insulating material, a plurality of gap unit holders mounted on the outer side of said cylindrical support to support a series of gap units arranged radially about the support and latwise to each other, each holder having spring contact pieces to bear against opposite sides of a gap unit 5. Spark gap apparatus, comprising a cylindrical support of insulating material, a plurality of gap unit holders mounted on the outer side of said cylindrical support to support a series of gapI units arranged radially about the support and fiat-wise to each other, a plurality of terminals mounted on the innen side of the support through which connections may be made for connecting any desired number of the gap unit lholders in the circuit,`a shaft mounted axially of the cylindrical support, a contact aim carried by said shaft having a spring contact piece for making contact with said termina-ls, and a hand piece for turning said shaft, said terminals and said contact piece being formed with coacting positioning faces whereby the proper positioning of the contact arm with relation to the terminals will be aided and will be manually indicated to the operator.

6. Spark gap apparatus, comprising :i plurality of independently removable spark gap units supported radially about and at approximately equal distances from a conimon axis with adjacent units flatwise to each other.

7. Spark gap apparatus, comprising a plurality of gapunit holders arranged to support a series of gap units radially about a common axis with adjacent units flatwise series 'spark gap units carried by said holders and for varying the number of units connected in the circuit comprising a series of terminals arranged about said common axis and a contact member for making contact with saidterminals to connect the holders in the circuit, said contact member being adjustable about said axis for varying the number' of units connected in the circuit.

9. Spark gap apparatus, comprising a plurality of spark gap units supported radially about and at approximately equal distances from a common axis Withadjacent units flatwise to each other, and means for directing against said gap units a current ofair moving in a direction of said common axls.

10. Spark gap apparatus, comprising a plurality of gap unit holders arranged to support a series of gap units radiallyabout and at approximately equal distances from a common axis with adjacent units ilatwise to each other, and a rotary fan mounted to turn on an axis approximately coinciding with said common axis for directing a current of air against the gap units held by said holders.

11. A spark gap unit, comprising a pair of electrode plates assembled together flatwise, the inner sides of said plates having opposed flat sparking faces and the outer sides of the plates opposite the sparkingv faces `being formed With ribs extending radially outward from the center of the plate to provide an extended heat-dissipating surface.

12. A spark gap unit, comprising electrode plates assembled together flatwise and secured together'by a single central bolt, the plates having their central portions of increased thiclmess as compared to the outer portions thereof and having their outer faces formed with radial ribs. l

13. An electrode plate for a spark gap having upon one side a sparking face of different metal from the body of the plate and having on its side opposite its sparkin face a'series of ribs to provide an extende heat-dissipating surface.

14. An electrode plate for -a spark gap having on one side an annular sparking face of different metal from the body of the plate and on the side opposite its sparkingI ace radial ribs to provide an extended heatdissipating surface. l

In testimony whereof I have hereunto set my hand in the presence of two subscribing Witnesses.

. LAWRENCE J. LESH. Witnesses:

ETHEL JoHNEs, A. L. KENT. 

